Processing of hydrocarbon mixtures from high-pressure gas liquid pipelines (e.g., from a dense phase pipeline or well-head fluid) is often problematic, especially where such mixtures contain relatively large quantities of C3, C4, and heavier components (e.g., 20 to 40 mol %). Among other things, all or almost all of the currently known configurations and methods require substantial amounts of energy for various heating and cooling processes, and at least some of the known processes have relatively low recovery levels for C3, C4, and heavier components.
For example, a typical known configuration for processing high-pressure hydrocarbon mixtures is described in U.S. Pat. No. 4,702,819 to Sharma et al. Here, relatively high C3 and C4+recoveries are achieved using external refrigeration (typical propane refrigeration) and heating. While such configurations allow for at least somewhat desirable levels of C3 and C4+recovery, effective operation is typically limited to temperatures below ambient temperature. Moreover, numerous heat exchangers and columns are needed for heat integration. In another known configuration, as exemplified in U.S. Pat. No. 4,462,813 to May et al., a multi-stage compressor is connected to wellhead, refrigeration unit, and separators. Similar to Sharma's configuration, May's configuration tends to be relatively inefficient and energy intensive where the high-pressure hydrocarbon mixtures comprises significant quantities of C3 and C4+components.
In still further known examples, as described in Re33408 or U.S. Pat. No. 4,507,133 to Khan et al., the vapor stream from a deethanizer is cooled to liquefaction and contacted with a vapor phase from the hydrocarbon feed stream to separate methane, ethane, and propane vapors from the feed. Similarly, as described in U.S. Pat. No. 6,658,893 to Mealey, the feed gas is cooled to liquefy the heavier components and at least some of the C2 and lighter components. Subsequent condensation and absorption steps then allow high recovery of C3 and C4+components. Such processes typically allow high yields of C3 and C4+, however, require substantial amounts of energy for cooling and pumping the liquids.
Alternatively, an absorber can be employed upstream from an expander, wherein the cooled vapor streams from the absorber are combined with the cooled and expanded vapor stream of a downstream distillation column as taught by Sorensen in U.S. Pat. No. 5,685,170. While such configurations advantageously make use of the pressure in the feed gas, a gas dehydration unit must be installed for the cryogenic expander operation, and residue gas in such plants needs to be recompressed which negates any cost or energy savings.
Thus, while numerous configurations and methods for gas condensate hydrocarbon separation are known in the art, all or almost all of them, suffer from one or more disadvantages. Therefore, there is still a need for improved configurations and methods for gas condensate separation, and especially for gas condensate separation from high-pressure hydrocarbon mixtures.